Compare the effects of increased FFA availability on insulin sensitivity in men and premenopausal and postmenopausal women. Determine the effects of elevated FFA on accumulation of products of hexosamine pathway and activity of the rate limiting enzyme of this pathway, the effects of elevated FFA on muscle long chain fatty acylCoA levels, and the relationship between induction of insulin resistance and accumulation of these intermediates in men and women. Determine the effects of elevated FFA levels under basal and insulin stimulated conditions on muscle expression of UCP-2 and UCP-3, whether this induction differs between men and women, and whether induction of UCP-2 and UCP-3 correlates inversely with accumulation of long chain fatty acyl CoAs.